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Age-Related Macular Degeneration (AMD or ARMD)(Senile Macular Degeneration)

Age-related macular degeneration (AMD) is the most common cause of irreversible central vision loss in elderly patients. Funduscopic findings are diagnostic; fluorescein angiography and optical coherence tomography assist in directing treatment. Treatment is with dietary supplements, intravitreal injection of anti–vascular endothelial growth factor, laser photocoagulation, photodynamic therapy, and low-vision devices.

AMD is a leading cause of permanent, irreversible vision loss in the elderly. It is more common among whites.

Etiology

Risk factors include the following:

  • Genetic variants (eg, abnormal complement factor H)
  • Smoking
  • Cardiovascular disease
  • Hypertension
  • A diet low in ω-3 fatty acids and dark green leafy vegetables
  • Age

Pathophysiology

Two different forms occur:

  • Dry (atrophic), in about 90% of cases
  • Wet (exudative or neovascular), in about 10% of cases

Ninety percent of the blindness caused by AMD occurs in patients who have the wet form.

Dry AMD causes retinal pigmentation changes, yellow spots (drusen), and areas of chorioretinal atrophy (referred to as geographic atrophy). There is no elevated macular scar, edema, hemorrhage, or exudation.

Wet AMD begins as dry AMD. Choroidal neovascularization (abnormal new vessel formation) occurs under the retina. Localized macular edema or hemorrhage may elevate an area of the macula or cause a localized retinal pigment epithelial detachment. Eventually, neovascularization causes an elevated scar under the macula.

Symptoms and Signs

Dry AMD: The loss of central vision is slow, painless, and usually mild. Central blind spots (scotomas) usually occur late and can sometimes become severe. Symptoms are usually bilateral.

Funduscopic changes include the following:

  • Pigment changes
  • Drusen
  • Areas of chorioretinal atrophy

Wet AMD: Rapid vision loss is more typical of wet AMD. The first symptom is usually visual distortion, such as a central blind spot (scotoma) or curving of straight lines (metamorphopsia). Peripheral vision and color vision are generally unaffected; however, the patient may become legally blind (< 20/200 vision) in the affected eye or eyes, particularly if AMD is not treated. Wet macular degeneration usually affects one eye at a time; thus, symptoms of wet AMD are often unilateral.

Funduscopic changes include the following:

  • Subretinal hemorrhage in or around the macula
  • Localized retinal elevation
  • Retinal edema
  • Gray discoloration of the subretinal space
  • Exudates in or around the macula
  • Detachment of retinal pigment epithelium

Diagnosis

  • Funduscopic examination
  • Fluorescein angiography
  • Optical coherence tomography

Both forms of AMD are diagnosed by funduscopic examination. Visual changes can often be detected with an Amsler grid (see Approach to the Ophthalmologic Patient: Visual field testing). Fluorescein angiography is done when findings suggest wet AMD. Angiography demonstrates and characterizes subretinal choroidal neovascular membranes and can delineate areas of geographic atrophy. Optical coherence tomography (OCT) aids in identifying intraretinal and subretinal fluid and can help assess response to treatment.

Treatment

  • Dietary supplements for dry or unilateral wet AMD
  • Intravitreal anti–vascular endothelial growth factor drugs or laser treatments for wet AMD
  • Supportive measures

Dry AMD: There is no way to reverse damage caused by dry AMD, but patients with extensive drusen, pigment changes, or geographic atrophy benefit from daily supplements of the following:

  • Zinc oxide 80 mg
  • Copper 2 mg
  • Vitamin C 500 mg
  • Vitamin E 400 IU
  • β-Carotene 15 mg (or vitamin A 28,000 IU)

Vitamin A is sometimes substituted for β-carotene. In smokers, β-carotene and vitamin A can increase the risk of lung cancer. For this reason, they are contraindicated in patients who have smoked in the previous 7 yr. Reducing cardiovascular risk factors, including eating foods high in ω-3 fatty acids and dark green leafy vegetables may help.

Wet AMD: Patients with wet AMD in one eye may benefit from daily supplements that are recommended for dry AMD. The choice of other treatment depends on the size, location, and type of neovascularization. Intravitreal injection of anti–vascular endothelial growth factor (VEGF) drugs (usually ranibizumab or bevacizumabSome Trade Names
AVASTIN
Click for Drug Monograph
or, occasionally, pegaptanib) can substantially reduce the risk of vision loss and can help restore reading vision in up to one third of patients. Thermal laser photocoagulation of neovascularization outside the fovea may prevent severe vision loss. Photodynamic therapy, a type of laser treatment, helps under specific circumstances. Corticosteroids (eg, triamcinoloneSome Trade Names
ARISTOCORT
KENACORT
KENALOG
NASACORT
Click for Drug Monograph
) are sometimes injected intraocularly along with an anti-VEGF drug. Other treatments, including transpupillary thermotherapy, subretinal surgery, and macular translocation surgery, are seldom used.

Supportive measures: For patients who have lost central vision, low-vision devices such as magnifiers, high-power reading glasses, computer monitors, and telescopic lenses, are available. Also, certain types of software can display computer data in large print or read information aloud in a synthetic voice. Low-vision counseling is advised.

Last full review/revision December 2008 by Sunir J. Garg, MD, FACS

Content last modified December 2008

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